1. Field of the Invention
The present invention relates generally to a method and an apparatus for distributing particles. More specifically, the invention relates to a method and an apparatus for transferring particles such as blocks to form electronic assemblies.
2. Background
The manufacture of electronic assemblies such as display panels is known in the art. One such method involves using fluidic self-assembly (FSA) that is described in U.S. Pat. No. 5,545,291. FIG. 1 illustrates that in FSA, blocks 102 with integrated circuits thereon are placed into a FSA fluid 104 such as water. The combination of the blocks 102 in the FSA fluid 104, referred to as a slurry 106, is dispensed over recessed regions 108 in a substrate 110. The recessed regions 108 receive the plurality of blocks 102 and the blocks 102 are subsequently electrically coupled.
Although FSA has provided advantages to electronic device manufacturers such as the increased speed of assembling an electronic device, several drawbacks may be associated with the FSA process. For instance, some blocks may fall to the surface of the substrate without settling into recessed regions. Blocks not settling into the recessed regions may be due to the weight of some blocks being heavier than the fluid causing the blocks to fall to the surface of the substrate in which a recessed region does not exist. Alternatively, some blocks may be dislodged from the recessed regions even after having been deposited into these regions. Blocks being dislodged from the recessed regions may be due to additional treatment to the substrate such as cleaning and removing excess blocks.
Having the blocks not being properly deposited into the recessed regions is problematic because devices manufactured with the recessed regions that lack a block generally operate less efficiently compared to devices in which all of the blocks have been properly placed. Improperly placed or absent blocks also lead to a lower overall production yield. A manufacturer may solve this problem by using a variety of methods. For example, the FSA process may be used a second time over the empty recessed regions. Applying a second FSA process, however, is expensive because it would require additional processing time, larger processing equipment in some cases, and additional blocks.
Another method involves using a robot to place a block into a particular recessed region. Typically the robot may not place more than one block into one of the recessed regions. Additionally, a typical robot system only has a 625 xcexcm accuracy. Moreover, using the robot is a time consuming and expensive process; for instance, a typical robot system has a placement speed of 2000-3000 units per hour.